Running a festival is a logistical nightmare; it takes a lot of people an awful lot of time to make sure everything runs even vaguely smoothly. If there's one person in the midst of this who has a pretty easy, highly paid job (show up, mime, go home) who refuses to do this, and thereby fucks up the day of all the hard-working, sleep-deprived, exhausted, under-appreciated festival crew, well, that pisses me off. It means everyone has to do a ton more work just to make sure that the people at the festival and all the other bands don't have their day ruined.

For some reason, doing this when you're holding a microphone makes you "artistic", "difficult" or maybe a "Diva". In any other walk of life it's called being rude, selfish and inconsiderate

You can read Turner's whole post here. According to Minaj's own Twitter feed she wasn't feeling well before her performance at the festival.